Having calibrated antenna systems are becoming increasingly important, in particular in future wireless communication systems, since the number of branches increases and since various beamforming technologies are to be supported. Future Advanced Antenna Systems is intended to provide both “standard beamforming” such as cell specific beamforming and user equipment (UE) beamforming in a controlled direction, as well as reciprocity based beamforming.
It is important that an antenna system is properly calibrated in order to ensure highest possible performance. A challenge in this regards is that the antenna system should support different types of beamforming, having different requirements.